This is a multicenter, nationwide study aimed at determining whether early intervention therapy in non-diabetic relatives of persons with Type-1 diabetes can delay their development of diabetes. Type I or Insulin Dependent Diabetes Mellitus (IDDM) arises in genetically susceptible individuals as a consequence of immune mediated destruction of the pancreatic islet insulin secreting B-cells. The onset of clinical symptoms of diabetes represents the end-point of a chronic and progressive loss of B-cell function, and it appears only when the majority of B-cells have benn destroyed. This trial has been designed to test whether intervention before the onset of clinical diabetes can prevent further damage of pancreatic B-cells and delay the expected development of clinical diabetes.